+_Black_ is already [successfully used](#used-by) by many projects, small and big. It
+also sports a decent test suite. However, it is still very new. Things will probably be
+wonky for a while. This is made explicit by the "Beta" trove classifier, as well as by
+the "b" in the version number. What this means for you is that **until the formatter
+becomes stable, you should expect some formatting to change in the future**. That being
+said, no drastic stylistic changes are planned, mostly responses to bug reports.
+
+Also, as a temporary safety measure, _Black_ will check that the reformatted code still
+produces a valid AST that is equivalent to the original. This slows it down. If you're
+feeling confident, use `--fast`.
+
+## The _Black_ code style
+
+_Black_ is a PEP 8 compliant opinionated formatter. _Black_ reformats entire files in
+place. It is not configurable. It doesn't take previous formatting into account. Your
+main option of configuring _Black_ is that it doesn't reformat blocks that start with
+`# fmt: off` and end with `# fmt: on`. `# fmt: on/off` have to be on the same level of
+indentation. To learn more about _Black_'s opinions, to go
+[the_black_code_style](https://github.com/psf/black/blob/master/docs/the_black_code_style.md).
+
+Please refer to this document before submitting an issue. What seems like a bug might be
+intended behaviour.
+
+## Pragmatism
+
+Early versions of _Black_ used to be absolutist in some respects. They took after its
+initial author. This was fine at the time as it made the implementation simpler and
+there were not many users anyway. Not many edge cases were reported. As a mature tool,
+_Black_ does make some exceptions to rules it otherwise holds. This
+[section](https://github.com/psf/black/blob/master/docs/the_black_code_style.md#pragmatism)
+of `the_black_code_style` describes what those exceptions are and why this is the case.
+
+Please refer to this document before submitting an issue just like with the document
+above. What seems like a bug might be intended behaviour.
+
+## pyproject.toml
+
+_Black_ is able to read project-specific default values for its command line options
+from a `pyproject.toml` file. This is especially useful for specifying custom
+`--include` and `--exclude` patterns for your project.
+
+**Pro-tip**: If you're asking yourself "Do I need to configure anything?" the answer is
+"No". _Black_ is all about sensible defaults.
+
+### What on Earth is a `pyproject.toml` file?
+
+[PEP 518](https://www.python.org/dev/peps/pep-0518/) defines `pyproject.toml` as a
+configuration file to store build system requirements for Python projects. With the help
+of tools like [Poetry](https://python-poetry.org/) or
+[Flit](https://flit.readthedocs.io/en/latest/) it can fully replace the need for
+`setup.py` and `setup.cfg` files.
+
+### Where _Black_ looks for the file
+
+By default _Black_ looks for `pyproject.toml` starting from the common base directory of
+all files and directories passed on the command line. If it's not there, it looks in
+parent directories. It stops looking when it finds the file, or a `.git` directory, or a
+`.hg` directory, or the root of the file system, whichever comes first.
+
+If you're formatting standard input, _Black_ will look for configuration starting from
+the current working directory.
+
+You can also explicitly specify the path to a particular file that you want with
+`--config`. In this situation _Black_ will not look for any other file.
+
+If you're running with `--verbose`, you will see a blue message if a file was found and
+used.
+
+Please note `blackd` will not use `pyproject.toml` configuration.
+
+### Configuration format
+
+As the file extension suggests, `pyproject.toml` is a
+[TOML](https://github.com/toml-lang/toml) file. It contains separate sections for
+different tools. _Black_ is using the `[tool.black]` section. The option keys are the
+same as long names of options on the command line.
+
+Note that you have to use single-quoted strings in TOML for regular expressions. It's
+the equivalent of r-strings in Python. Multiline strings are treated as verbose regular
+expressions by Black. Use `[ ]` to denote a significant space character.
+
+<details>
+<summary>Example `pyproject.toml`</summary>
+
+```toml
+[tool.black]
+line-length = 88
+target-version = ['py37']
+include = '\.pyi?$'
+exclude = '''
+
+(
+ /(
+ \.eggs # exclude a few common directories in the
+ | \.git # root of the project
+ | \.hg
+ | \.mypy_cache
+ | \.tox
+ | \.venv
+ | _build
+ | buck-out
+ | build
+ | dist
+ )/
+ | foo.py # also separately exclude a file named foo.py in
+ # the root of the project
+)
+'''
+```
projects / etc / vim.git / blobdiff